MX2010014443A

MX2010014443A - Apparatus and method to locate an object in a pipeline.

Info

Publication number: MX2010014443A
Application number: MX2010014443A
Authority: MX
Inventors: Peter O Paulson
Original assignee: Pure Technologies Ltd
Priority date: 2008-06-25
Filing date: 2009-06-25
Publication date: 2011-04-04
Also published as: NZ590023A; AU2009261918A1; AU2009261918B2; CA2728818A1; IL210146A0; EP2297591A4; US20110103189A1; IL210146A; BRPI0915515A2; EP2297591A1; CN102132170A; EA201170081A1; WO2009155708A1

Abstract

Apparatus for locating an object in a pipeline, comprising a transmitting station having means for transmitting in the pipeline acoustic emissions having a frequency in the range from 20 KHz to 200 KHz; a receiving station having a receiver capable of receiving the acoustic emissions transmitted by the transmitting station; one of the receiving station and the transmitting station being located at a known position on the pipeline and the other of the receiving station and the transmitting station being located on the object; and clock means to determine the time taken for the acoustic emissions to travel between the transmitting station and the receiving station.

Description

APPARATUS AND METHOD FOR LOCATE AN OBJECT IN A PIPELINE The present invention relates to an apparatus and method for locating an object in! A pipe. Particularly, it relates to an apparatus and a method for locating a moving object which has been introduced into the pipe. In its preferred modalities, it is related to! locating the position of a detection unit to detect anomalies in pipes that transport liquids, such as for example oil or water, or gases, such as for example natural gas. i DI SCUS ION OF THE PREVIOUS TECHNIQUE It is often useful to know the position of an object that has been introduced into a pipeline, for example, for maintenance or leak detection purposes. For example, some v e c e if it is necessary to know the position of a pipe cleaning block that has been introduced to clean a pipe. The knowledge of the position allows an operator to predict when the cleansing block will arrive at a cleansing block station, or to perform: the steps to release it if it has jammed.

I A particular type of object, which would be useful to know its position within the pipeline at a particular time, is a detection unit that detects the conditions in the pipeline. | Unmounted detection units that move through a pipe, which detect conditions when moving, have been known for many years. For example, the petroleum industry has long used untapped "cleansing blocks" which fill the cross section of the pipeline and which are pushed through the flowing oil. In both oil and water pipes, unblinded ball-like detection units have been used, such as that shown in the published PCT application WO 2006/081671 of Puré i Technologies Ltd. In the currently preferred form of the published application detection unit, the units roll along the bottom of a pipe filled with fluid, pushed by the fluid flow. There are also energized detection units not moored, which pass through the pipeline! by means of its own motive energy. , The detection unit is typically placed in the pipeline to detect anomalous conditions such as leakage, corrosion or defects of the pipe wall, using suitable known sensors to detect the particular anomalous condition. Obviously, it is necessary to determine as precisely as possible the location of the anomalous condition, in such a way that it can be remedied or monitored further. To determine this location, it is usually important to know the location of the detection unit at the time the abnormal condition is observed. In most cases, methods that use satellites (for example a GPS tracking device) no! They are usable, because the pipe is buried deep in the subsoil for these methods to work.

Several methods have been used to determine the location of the detection units' inside the pipes. It can be done | a i I crude determination for detection units that are transported by the fluid flow knowing; the average speed of the flow of the liquid inside the pipe, and recording the time elapsed from when the unit was released to pass through the pipeline until it reaches the anomaly. This method is sometimes refined by having beacons that emit particular sound signals at intervals along the pipeline (for example, at inspection ports) and using the times at which the detection unit passes the beacons to help calibrate the average flow velocity for particular sections of the pipe. If the detector is designed to roll along the bottom of the pipe, the number of revolutions can be counted to provide an indication of the distance traveled. If the detection unit is equipped with a magnetometer, it can detect elements of the pipe architecture such as welds in a metal pipe or bell and spigot and bell joints in a pipe made of concrete with wire wrap. Similarly, sensors of Pressure and temperature in the detection unit || often detect elements of the architecture [of the tube such as the places where other lines join or leave the pipe that is being monitored, because the liquid that comes out or joins The pipe that is being monitored affects the pressure or temperature in that pipe.

Although these methods of determining the location of the detection units are useful / they do not provide an accurate location for the detection unit. The flow of fluid inside a pipe may not be constant, especially if the pipe is partially filled with liquid or if it is going up or down. The measurement of the number! from 52-693 i i Revolutions made by a rolling detection unit can sometimes be incorrect if the unit is dragged in the fluid in the pipe and loses contact with the bottom of the pipe. The detection of the architecture of the pipeline may not be feasible if only incomplete or imprecise records exist of the locations of the architectural features.

It would therefore be useful to have an accurate and precise method of determining the location of an object that has been introduced into a pipe, particularly a detection unit within the pipe, and to have an apparatus for carrying out that method. i BRIEF DESCRIPTION OF THE INVENTION It has now been discovered that a high frequency acoustic emission is transmitted through pipes with little loss in amplitude. This allows! that the broadcast is received at a remote location; for example, several kilometers, without excessive attenuation.

If the precise time of sending the acoustic emission through the pipeline from a first site is determined, and the precise time in which that emission is received at a second possible remote site in accordance with the invention is determined, obtain very accurate measurement of the length of the pipe between the shipping site and the receiving site. To get i the distance between the two sites, the time it took for the acoustic emission to move between the two sites is determined, and this is multiplied by the speed of sound of the particular frequency in the type of liquid inside the pipeline. When any ^ of the first and second site is a moveable object inside I of the pipe and "the other is a known position along the pipeline, this provides a method find the site of the movable object. i i DRAWINGS The invention will be described with reference to the drawings, in which: i Figure 1 is a representation (n'o to scale) of a detection unit equipped with a transmitting station according to the invention, and located within a pipeline, wherein the detection unit is a non-moored ball that rolls along the bottom of the pipe. The pipe is shown in section in order to show the detection unit.

Figure 2 is a representation (not to scale) of a detection unit equipped with a transmitting station according to the invention, and 52-693! I located inside the pipe, where the detection unit is a pipe cleaner. The pipe is shown in section in order to show the detection unit.

Figure 3 is a representation (n to scale) of a receiving station according to the invention, located at a known location on the i pipe, and other equipment associated with it. The pipe and the surrounding earth are shown in section with the! order to show the receiving station. ! Figure 4 is a representation (n to scale) of an alternative embodiment of the invention, I showing a transmitting station on a pipeline and a detection unit equipped with a receiving station. The pipe and the surrounding earth are shown in section in order to show the receiving station and the detection unit.

DETAILED DESCRIPTION OF THE INVENTION According to the invention, a transmission station has a precise clock, and a means for emitting a high frequency acoustic emission. At least one receiving station has an acoustic receiver positioned to receive sounds originating within the pipe, a precise clock and a device; from 52-693 I registry. The difference (if any) between the readings of the two clocks at the same time is known, so that a correction can be made when calculating the time it takes an emission to travel between them. Preferably, the transmitting station is in a movable detection unit and the receiving device is in a fixed position in or attached to the pipe. The reason for this is that electric power is usually more readily available at a fixed site (where it can be supplied from an electrical network) than at a mobile device that depends on batteries or the like. An abundant electric power supply to the receiving station allows said station to be provided with amplifiers to amplify the received signal. ' In the preferred embodiment, the transmitting station is located on a non-moored detection unit and the receiving station is located at a known fixed point in the pipeline, such as; for example, the point at which the detection unit was thrown into the pipeline or a point at which the pipeline is accessible through an inspection port. ( In a less preferred embodiment, the transmitting station is at a known fixed point in the 52-693 I pipe and the receiving station is on the detection unit not tied.

In another useful embodiment when recording a pipe of unknown configuration wherein the speed of sound in the fluid inside the pipe is known, the transmitting and receiving stations are located at fixed points along the pipe, and the invention it is used to determine the precise distance between the fixed points.

In another embodiment, useful when calibrating the system, both stations are fixed points along the length of the pipeline at a known distance from each other, and the invention is used to determine the speed I precise sound and frequency used in the type ! > ! of fluid inside the pipe. : i When the transmitting station is located on a movable sensing unit, it is particularly preferred to have several receiving stations in use at different locations along the pipeline. The transmitting unit on the movable detecting device transmits its acoustic emission to lta frequency. Depending on where the movable detection unit is located at any particular time, the emission may be received at different receiving stations, or at several receiving stations at the same time. weather. Emissions received at any station are used to calculate the distance of the movable detection unit from that station.

From time to time the clocks in the transmitting and receiving stations are synchronized, in such a way that compensation can be made for any error in their readings. Conveniently, this is done by determining the difference in the readings of; the clocks in the same absolute time, in such a way! that the difference (the error) between its readings is known.

This can be done, for example, by comparing each clock with a GPS time signal (which is construed for this purpose as the "correct" time), and the difference between the time reading of G! PS and the reading is noted. of the clock. This can be done either before or after the detection unit moves down the pipe and emits the acoustic emissions! which are received in the receiving units. If commercially available high precision clocks are used, there will be little entrainment and synchronization does not need to be made each time it is caused, the movement of the movable sensor unit through the tube. A person with experience in the art will know how often to synchronize, considering the precision of the clocks that are used and the required accuracy.

In the operation according to the invention, a high frequency acoustic emission is created in the transmitting station at a known time with precision. The acoustic emission is received at the receiving station and the reception time is noted. From these observations, the duration of the time it took for the acoustic emission to pass through the liquid in the pipeline from the transmitting station to the receiving station is determined. If the sound velocity of the frequency used in the type of liquid within the pipeline is not known, it is determined. Then the distance between the two stations at the time of the emission is determined by multiplying the duration of the time it took for the acoustic emission to pass through the liquid in the pipeline by the speed of sound of the frequency used in the type of liquid inside the pipe.

The means for emitting the acoustic emission in a known time with precision is preferably a chronometer that causes emissions at intervals; of precise time. If the chronometer1 is not present, it is not absolutely necessary to have an associated recording device, as long as the reading. of the clock is known for any emission, because (the 52-693 I Clock readings for other emissions can be derived from it. However, it is preferred to have a recording device which shows the time of each transmission recorded by the associated clock.

Alternatively, if the transmitting station is on the detection unit, a means for emitting I the acoustic emission can be an alarm that causes an emission when a sensor on the detection unit detects a reading beyond a limit preset or other predetermined alarm condition, together with a recording device that records the precise time at which the acoustic emission was recorded by the associated clock.

As stated above, the invention uses a high frequency acoustic emission .; The usable frequencies depend on the nature of the fluid in the pipe and the diameter of the pipe. Generally, low frequencies (below about 500 Hz) are transmitted for fairly long distances along the pipe, but np are used in the present invention because they are transmitted both through the liquid and the walls of the pipe, such that the signal received at the receiving station is a combination of the emission traveling through the liquid and the walls. 52-693 I Above 500 Hz, within a frequency range that varies with the type of fluid within the pipe, the emissions are absorbed or damped by the fluid within the pipeline. 'This damping or absorption decreases with increasing frequency and varies with the type of fluid. For most fluids, damping is significant at frequencies in the interval! approximately 500-18000 Hz, in such a way that they must I avoid these frequencies. For gases,; the damping depends on the pressure of the gas as well as its composition, but generally the frequencies below 18000 Hz can be found with a damping, especially when the gas is i pressurized. The frequencies above are usable i of those to which the damping or absorption is significant for the particular fluid.

To avoid any probability of damping or absorption, it is preferred to use a frequency greater than 20 KHz, preferably in the range of 20-100 KHz, and more preferably in the range of 30-80 KHz. Generally, frequencies in, are particularly preferred.

I 40 KHz-80 Khz range in pipes containing water, and frequencies are particularly preferred in the I 52-693 range of 30 Khz-80 KHz in pipes containing oil. Frequencies above 100 KHz, for example up to 200 KHz, can also be used, but are generally not preferred, because the high sampling rate required to receive these frequencies usually requires more complicated equipment than necessary for lower frequencies. i Depending on the size and construction of the transmission station, when the detection unit carries the transmission station, some frequencies within these ranges may resonate in the unit.

I detection. It is preferred to use a resonant frequency i when possible when the detection unit has the transmitting station, because it is easier to create a high amplitude sound at a resonant frequency1 than at other nearby frequencies.

Conveniently, the acoustic emission must have a duration of at least 1 ms. However, to distinguish it from possible high frequency evanescent noises within the pipe, a longer emission is preferred, from 20 ms to 200 ms. If desired, longer emissions can also be used.

The emissions are spaced one from the other for a time longer than the duration of the emission, so that the successive emissions do not | HE I overlap or interfere with each other at the receiving station. However, they are sufficiently frequent in such a way that, at the speed at which the moving object moves, they serve to locate the object with the desired degree of precision. For objects that drift in the fluid flow in the pipe, at typical pipe flow rates, sufficient location accuracy is obtained for most purposes if the emissions are repeated every 1 second for up to 15 seconds.

Although it is suitable for most situations: use a broadcast at a frequency I In particular, it is also possible to send a predetermined set of tones comprising empty frequencies in a predetermined order. Therefore, for example, a set of tones could be | a sequence of four emissions of 6 ms. , each one with a length of 42 KHz, 40.5 KHz, 39.0 KHz and 38 KHz. A set of tones like this can be used when transient high frequency noises are expected in the pipeline from other sources. The receiving station can be designed to recognize only signals that have these frequencies in this order. At distances of several kilometers, there may be some overlap of the signals at different frequencies, caused by the 52-693 reflection of the signals from the walls of the pipe or the architecture such as valves, but the sequence of the signals is still recognizable.

It is surprising that high frequencies1 propagate over long distances through a pipeline, although normally such frequencies would normally be expected to attenuate rapidly in a liquid medium. Although the inventor does not wish to be bound by any theoretical explanation, it is believed that the walls of the pipeline act in a manner analogous to a waveguide to propagate high frequency acoustic emissions.

The invention is operable at all conventional pipe pressures, from subatmospheric pressure to high pressures. The invention will also operate on pipes filled with gas and pipes filled with liquid. In pipes where there is liquid with gas on it (as \ for example in a pipe that has water with iaire i above it), there must be a continuous path in, at least one phase (the liquid phase or gas) from the transmitting station to the receiving station. A continuous path through the liquid is preferred.

In a particularly preferred embodiment, the transmitting station is on a detection unit i and a receiving station is at the launch point of the detection unit within the 52-693 i pipe or in an inspection port along the pipeline or at the intended recovery site of the pipe detection unit. There may be several receiving stations if desired. In a method of 'using this apparatus, the transmitting unit transmits an acoustic emission at fixed intervals. The intervals are chosen depending on the expected displacement speed of the detection unit through the pipeline, so that an acoustic emission will occur when it is expected that the detection unit has traveled approximately a desired distance. The detection unit is provided with sufficient battery capacity in such a way that emissions can be generated at the desired time intervals during travel through the entire length of the pipe that the detection unit expects to inspect. Also, the emissions are sufficiently spaced in such a way that there is a sufficient interval to avoid overlap in thereceiving. For example, it is appropriate in most cases to establish that acoustic emissions occur at intervals from about 1 1/2 seconds to 2 minutes or even longer. Preferred ranges are from 1 second to 10 seconds.

The detection unit is launched and left 52-693 I move through the pipeline to a recovery point, the length of pipe being I inspected between the launch point and the recovery point. The detection unit is provided with conventional sensors such as for example a hydrophone, a magnetometer, a temperature sensor and the like to detect anomalies. When passing through the area to be inspected, the detection unit emits the acoustic emissions at predetermined intervals, and simultaneously the sensors It collects data about the condition of the pipeline.; In a less preferred embodiment, instead of having acoustic emissions emitted at established time intervals, an emission occurs whenever a sensor detects an anomaly, such as a result outside a predetermined interval or when there is a particular condition. This ensures that an accurate distance can be recorded from the receiving station for an abnormal reading of the sensor, to allow tracking of the site where the anomaly was observed. For this modality to work properly, the precise time of sending the broadcast must be recorded. This can be done by recording 'the sensor results along with the time trail! what shows the time as recorded by the clock. The precise time of sending the emission can be determined by examining the trace to see the time in which the i sensor recorded the anomalous result. For convenience, I The broadcast can also be recorded on the time trail. i At the recovery point, the detection unit is removed from the pipe in a known manner and the data is discharged therefrom. The sending time of each emission is compared with the records of the i reception of that emission at the receiving station !. The time of sending and receiving are standardized by correcting any error between the clocks (determined by the synchronization, which is carried out as needed), and the transmission speed of the sound of the emission frequency in the liquid is known or determined empirically. From this information, the distance covered by each emission is calculated by multiplying the time it took for that emission to travel between the transmission station and the receiving station. i This provides a set of data that shows the location of the detection unit when each acoustic emission was sent (if the detection unit carries the I i transmitter station) or received (if the detection unit carries the receiving station). The registers i 52 -. 52 - 693 I of the observations made by the sensors on the movable detection unit and the times in which they were made correlate with this information. This allows to determine the location of the detection unit at the moment of any abnormal reading of the sensor, in the distance traveled by the unit of detection.

I detection in the interval between the acoustic emissions immediately before and after it. Even more precision can be obtained by interpolating data within the range. Of course, in the mode in which the detection unit carries the transmitting station, even more precision is possible if the sensor is set to activate an emission precisely when an abnormal reading of the detector occurs.

This information can also be used to determine the speed of the detection unit in the pipe, plotting the position of the unit; of detection in time of the successive emissions at intervals of time spaced, and scoring; the I distance traveled in the interval between 'the? emissions. This information can be used to correct distance measurements made by other conventional measurement techniques. Also, the speed determined for the unit can be interpolated i detection when approaching a receiving unit and i then move away from the receiving unit to find precisely the time in which the detection unit 1 passes through the receiving unit. i If desired, the emissions can be sent to I predetermined time intervals and additional broadcasts can be sent (using a frequency or a set of tones different from the frequency or i set of tones for the emissions or the established time intervals) when a sensor detects an anomalous result. This allows the tracking of: the distance traveled by the detection unit and the correlation of said information with the results of the sensors, while providing information when an anomalous condition is found.

In a less preferred embodiment, 'acoustic emissions are sent at predetermined time intervals from a transmitting station at the launch point, the recovery point, or at some other point along the pipeline, for example] a site between the two where there is access to the pipeline through an inspection port. The receiving station is on the detection unit. < The recovery and processing of the data are essentially the same. This arrangement does not allow sending an emission when the detection unit 52-693 detects an abnormal reading of the sensor.

In general for liquids, sufficient accuracy for the speed of sound is obtained using manual values for the sound velocity of the frequency used through the type of liquid in the pipeline. However, the speed does not change; with temperature and pressure, so that better accuracy can be obtained by doing a calibration. 'For gases, manual values are less reliable, because the pressure in the pipe fluctuates when the gas is pumped, so calibration is recommended. 1 To make the calibration, the transmitting station is placed at a known location in the pipeline, such as an inspection port or a cleaning block release station, as shown in Figure 4 at 500. The receiving station is placed at a second site along the pipe, such as another inspection port or a cleaning block receiving station as shown at 400 in FIG. 4, whose location is a known distance along the pipeline from the station transmission. The detection unit is not used while the calibration is being made. Preferably the two sites are less than 1 km from each other and there are no inflections pronounced in the pipe between them. An acoustic emission is then transmitted at the desired frequency from the transmitting station at a known time to the receiving station. The time in which it is received is then recorded. Then the time elapsed for the broadcast to travel from the transmitting station to the receiving station is obtained by subtracting the time of sending the received time, with any necessary calibration correction. As the distance traveled between the two stations is known, the The speed of sound in the liquid or gas is obtained by dividing the distance between the elapsed time.

The invention can also be used to measure the length of an unknown pipe length between two sites accessible from ground level. The pipe, being underground, may have curves not evident from ground level, so that its length may not be determinable from ground level. To measure its length, a transmitting station is set up as shown at 500 in Fig. 4 at a site, and a receiving unit is established as shown at 400 in Fig. 3 at the second site. Preferably, the two sites are as close as is conveniently possible, in relation to the available soil sites, and the pipeline is 52-693; filled with liquid which has a speed. of the known sound at the chosen frequency. At least one acoustic emission at the chosen frequency is sent from the transmitting station at a known time to the receiving station. The time in the I which is received. After the time elapsed for! that the emission moves from the transmitting station to the receiving station is obtained by subtracting the time of sending the received time, with any necessary calibration correction. As the speed of sound in the liquid is known, it is found: the distance multiplying the speed of the sound by the elapsed time.

With reference to the drawings, Figure 1 shows a pipe 10, which contains the fluid 11 which may be, for example, oil, water or natural gas. The pipe is buried in the earth! 12. There is a leak 14 in the pipe, and the fluid 13 is' leaking from the leak to the ground as shown in 13.; The transmitting station, in this embodiment, is contained in the detection unit 100, which in this illustrative example is a ball sensor unit similar to that shown in the published PCT application WO 2006/081671 by Puré Technologies Ltdi La 52-693 i 1 The detection unit comprises a ball-shaped sensor unit 101 within a protective outer shell of urethane foam 104. Arrow 19 shows the direction of fluid flow. As the The detection unit is denser than the fluid, it rolls along the bottom of the pipe, pushed along by the fluid flow 19.

In the sensor unit 101 there are conventional sensors 203 and 204, for example! a magnetometer 203 and a hydrophone (acoustic sensor), 204.

A hole 103 is provided in the foam protective cover 104 to allow the hydrophone 204 to be in direct contact with the liquid 11.

I Also in the sensor unit 101 is a precision clock 202. This is connected to the acoustic emitter 201, which can emit acoustic signals at a preselected frequency within the range of 20-100 KHz. The acoustic emitter can be, for example, a piezo crystal of 19 mm (3/4") diameter x 2.5; 4 mm (1") thick. The acoustic emitter is arranged to emit an acoustic signal at set time intervals, for example once every 3 seconds.

Alternatively or in addition, the acoustic emitter 201 may be a tone generator which may emit a preselected sequence of signals acoustic at frequencies in the range of 20-100 KHz. Preferably, there is a hole 102 in the foam protective cover 104 in such a way that the acoustic emitter transmits directly to the fluid 11.

A memory device 205, which can be an SD memory card with encional commercially available or flash memory, is linked by means of suitable circuits 206 for i record data generated by sensors 203 and .204. Conveniently, the memory device 205 also records a continuous time trail of the clock, such that the precise time of each piece of data recorded by the sensors 203 and 204 is recorded. It is also possible for the memory device to record e '. n the same time trace of each acoustic emission, but This is not absolutely necessary, because acoustic emissions occur at established time intervals which are governed by the clock. In some cases (such as when a sensoir is a hydrophone that detects high frequencies), the data recorded by the sensor will include the periodic acoustic emissions in its recorded data.; In a preferred embodiment, the acoustic emitter 201 is a tone generator, and is linked to one or more sensors 203 and 204, such that the emitter Acoustic will send an acoustic emission which is a specific set of tones when the sensor detects a value outside a predetermined interval.

The battery 207 supplies power for the elements 201-205 through the circuits 206. ' In Figure 1, the detection unit 'passes adjacent to the leak 13. The hydrophone 204 detects the sound of fluid leaking from the pipe, and the' register 'of this sound is recorded in the memory device 205. The data that show the time of each acoustic signal are also recorded in the memory device 205. j Figure 2 shows an alternate modality. In Figure 2, similar items are marked with i the same numbers as in figure 1.

In Figure 2, the detection unit is a pipe cleaning plug 300 held in its position in the pipe 10 by means of seal flaps 301 and pushed along the pipe by the fluid flow in the pipe as it is indicated by means of arrow 19. In this embodiment, fluid 11 can; for example, petroleum or a petroleum refined product, because the pipes for such products use cleaning plugs for inspection pipes, and they are supplied in plugs stations cleaning where the cleaning plugs can be inserted or removed from the pipe. Conventional sensors 203 and 204 are found in the cleaning pad, for example a magnetometer and a hydrophone (acoustic signal) 204. The hydrophone 204 has its detection portion on an external surface of the cleaning pad in such a way that it can detect events in the surrounding fluid 11.

As in the embodiment of Figure 1, the detection unit of Figure 2 contains an accuracy clock 202 connected to an acoustic emitter 201 i which can emit acoustic signals at a preselected frequency in the range of 20-100 KHz, or whether If desired, it can emit a preselected sequence of acoustic signals at frequencies in the range of! 20- i 100 KHz. A memory device 205, which may be a flash memory or conventional SD card, is linked by means of suitable circuits 206 for recording data generated by sensors 203 and '204. The memory device 205 also registers! a continuous time trail of the clock, such that the precise time of each piece of data recorded by the sensors 203 and 204 is recorded. A 207 s battery supplies energy for the 201-205 elements through i of the circuits 206. The acoustic emitter is dispujesto 52-693 to emit an acoustic signal at set time intervals, for example once every 5 seconds.

The detection unit of FIG. 2 passes adjacent to the leak 13. The hydrophone 204 detects the sound of the fluid leaking from the pipe, and the recording of this sound is recorded in the memory device.

I 205. The data showing the time of each acoustic signal is also recorded in the memory device 205.

Figure 3 shows a receiving station 400. Again the same numbers are used to identify the same objects. Typically, the receiving station is in the access port where the detection unit has been inserted into the pipe, or in the access port where it will be removed, or in an intermediate inspection port between the two. having several intermediate receiving stations along the length of the pipeline being examined, for example at inspection ports, if possible at intervals of each kilometer or the like. In Figure 3, the receiving station is located at the inspection port 413, intermediate between the access port for the insertion and the access port for removal. The precise geographic location of access port 13 is known, either by locating it from: drawings of the pipeline and maps or locating it by means of a GPS reading.

In the inspection port 413, an acoustic receiver 401 which is capable of receiving, the frequencies generated by the acoustic emitter 201 of Figure 1 or Figure 2 is located in contact with the fluid 11 or otherwise in contact with a portion of the tube wall or other accessory through which the sound can pass at the operating frequency without significant attenuation. In Figure 3 there is shown at 401a an alternating position of acoustic receiver 401 > on the outside of the tube, with circuits 402a (shown as a dotted line) that connect it to other components. Although better reception of the sound is obtained if the receiver 401 is in contact with the liquid 11, it is often more convenient for the 1 maintenance place the receiver in contact with the tube as in 401a or an attached accessory such as an inspection port, and this usually provides adequate sound pickup. Of course, if an acoustic receiver is placed in contact with the fluid, as shown at 401, no receiver is needed in the alternate position at 401a and the circuits 402a are not necessary.; An amplifier 402, a memory device 403 and a precision clock 404 are connected to the receiver 401. Power is supplied to the clock, the memory device and the receiver by means of: a power source, shown here as a .405 battery, and all are connected by means of the circuits 406. For easy access, the clock, the memory device and the battery are located at or above ground level 17. The clock 404 has been synchronized with the clock 202 before the detection unit is released in the pipe, in such a way that the error between them is known when measuring the same time. ! In operation, the acoustic emitter 201 of the ball sensor unit of Figure 1 or the pipe cleaner plug of Figure 2 emits signals at predetermined intervals at a predetermined frequency. If desired, instead of a signal at a predetermined frequency, the acoustic emitter '201 i can emit groups of signals at frequencies I predetermined in a predetermined order to such I predetermined intervals. The events detected by sensors 203 and 204, together with the continuous recording i of the time shown by the clock 202, are recorded in the memory device 205. It is not necessary to record the times of the acoustic emissions in the memory device (although if desired this is 52-693 it can do), because the emissions occur at predetermined intervals, and the time of the first emission is known because the acoustic emitter 201 is enabled at the known time when the detection unit is released in the pipeline. Additionally, if the hydrophone 204 captures the frequency at which the signals are emitted, its registration will provide a record! of said signals.

The fluid 13 exiting the leak in the pipe 14 emits noise when the fluid leaves the pipe. This noise, indicated as wave fronts 16; it is picked up by the hydrophone 204 and the memory device 205 is recorded along with the other events detected by the sensor 204. i Optionally, the memory device may have associated software which recognizes that an abnormal data piece has been registered and causes the acoustic emitter 201 to immediately send a sequence of tones. This sequence is different from any tone or frequency sent at a predetermined interval, and provides information that will provide an exact location at which the anomalous data has been acquired.

Normally, however, it is not necessary to do this, because a sufficiently accurate location can be obtained by interpolating the anomalous data í between the signals sent at the predetermined intervals.

The acoustic emissions 215 pass through the fluid in the pipe, and are received by the receiver 401 or 401a (Figure 3). In a preferred embodiment, the acoustic receiver has associated software which compares the known send time of each acoustic emission (which is known because the clocks of the receiving station and the transmitting station are synchronized) with the arrival time of the receiver. that emission and multiplies the difference by the speed of the sound of that frequency to provide a real-time position of the detection unit in the pipeline. This is particularly useful when the receiving station is at the site where the pipe detection unit will be retrieved, because it allows an operator at that site to see the real-time position of the detection unit and make preparations. for your recovery.

If this preferred mode is used, | the real-time position of the detection unit is recorded directly. Otherwise, the time of i precise reception of each emission as shown by the clock 404 is recorded in the memory device 403.; I 52-693 After the desired inspection has been made, the contents of the memory devices 403 and 205 are examined. When abnormal readings have been made, or readings indicating a condition of interest, by means of the sensors, the time is recorded in that they are recorded in the memory device as they were observed. The acoustic emissions emitted at periodic intervals that! they are close to the observation time (and any special acoustic emission, if done, when the anomalous result was observed) are compared with the record of reception of those emissions at the receiving station. The time delay between sending and receiving each emission, multiplied by the speed of sound of that frequency in the liquid which is in the pipeline, provides a very accurate measurement of the distance between the detection unit and the station. receiver at the time the broadcast was sent. This accurately locates the site of the detection unit, and therefore the sensor, when the anomalous signals were detected by the sensor, so that additional testing or repair of the pipe can be carried out. The accuracy of the location of course decreases with the distance of the detection unit from the receiving unit in 52-693 where the results are received. Therefore, it is preferred to have receiver stations spaced along the pipeline, and to examine the relevant emissions received by at least two receiving stations. ! The error between the clocks at the receiving stations and the transmitting station is preferably determined at the beginning or at the end (or both) of a passage of a detection unit through the pipeline by comparing with a common standard such as a time signal. of GPS. If the detection unit is sent through a pipe for an inspection that lasts several hours, there may be some displacement, I depending on the accuracy of the clocks used. i Generally, watches that are commercially available are accurate at approximately 1 millisecond per hour. More precise clocks can be obtained commercially but they are more expensive. 1 A shift of several milliseconds per hour can be tolerated without unduly affecting the accuracy of the results, because each time the detection unit passes a known location, such as a beacon or receiving station, a correction factor can be applied for the displacement.

Figure 4 shows an alternative modality in 52-693; which the transmitting station is located in a Í access port, and the receiving station is located on a detection unit. The same numbers as in the previous figures are used to indicate 'the same objects as in the previous figures.1 The figure is not to scale and the jagged lines ^ 600 indicate that there is a pipe length of several hundred meters of length that have been omitted between the parts shown on both sides of the toothed line.

Figure 4 shows a transmitting station 500 located in an access port. The station I The transmitter has a precision clock 502. This is connected by means of circuits 504 to an acoustic emitter 501, which can emit acoustic signals at a preselected frequency within the range of 20-100 KHz. The acoustic emitter can be, for example, a piezo crystal of 19 mm (3/4") in diameter x 2.54 mm (1") in thickness. The acoustic emitter is arranged to emit an acoustic signal at set time intervals, for example once every 3 seconds. Preferably, there is a memory device 1 507 which records the acoustic signals and the time of emission of each of these signals. | Alternatively or in addition, the acoustic emitter i 52-693 I 501 can be a tone generator which can emit a preselected sequence of signals acoustic at frequencies in the range of 20-100 KHz. i The acoustic emitter is shown being in contact with the fluid 11. However, if desired, the acoustic emitter can be placed in an alternative location 501a in acoustic contact with the pipe (shown here as the cover of the access port 513). and being connected to the clock 502 by means of the circuits 504a.; ' The power source 503 energizes the clock and the acoustic emitter through the power circuits 505. í In this embodiment the receiving station is mounted on a detection unit, illustrated here as a cleaning pad 540 similar to cleaning pad 300 shown in FIG. 2. As in FIG. 2 !, the detection unit 540 contains a precision clock 202 and sensors 203 and 204. As previously discussed, sensor 204 is a hydrophone. J A memory device 205, which may be a flash memory or conventional SD card, is linked by means of suitable circuits 206 for recording data generated by the sensors 203 and 204. The memory device 205 also records a trace 52-693, I I of time / continuous clock, such that the precise time of each piece of data recorded by the sensors 203 and 204 is recorded. A battery 207 provides power for these elements through the circuits 206.

However, unlike the cleaning pad in Figure 2, the cleaning pad 540 does not have an acoustic emitter. Instead, there is an acoustic receiver 550 which is capable of receiving the emissions generated by the acoustic emitter 501 of the transmitting station 500. If necessary, the received sound is amplified by means of an amplifier 551, and j 'is recorded. with the traces of the clock 202 and the sensors 203 and: 204 in the memory device 205. If the hydrophone 204 is designed in such a way that it can pick up the frequency or frequencies emitted by the acoustic emitter 501, then it can be omitted. receiver '550 and the 551 amplifier, and the hydrophone can work I as well as an acoustic sensor for leaks and the like as the receiving station for the invention. , i In operation, the acoustic emitter 501 or 501a outputs signals at a predetermined interval one of the other at a predetermined frequency. If desired; instead of a signal at a predetermined frequency; acoustic emitter 501 or 501a can emit groups! from 52-693: signals at predetermined frequencies in an order Í predetermined to said predetermined interval.

I In the cleaning pad, the receiver 550 (or hydrophone 204, if it can pick up the appropriate frequency) receives emissions sent by the acoustic emitter 501 or 501a. The broadcasts (which are amplified if necessary by means of the amplifier 551), the events detected by the sensor 203 and the hydrophone 204, together with a continuous record of the time shown by the clock 202, are all recorded in the memory device 205 The fluid 13 that emerges from the leakage of the tubing 14 emits noise when the fluid leaves the tubing. This noise, indicated as wave fronts 16, is picked up by the hydrophone 204 and the memory device 205 is recorded along with the other events detected by the sensor 204. 1 After the desired inspection has been made, the contents of the memory 205 and the device I 507 memory are examined, and the traces of the clock are adjusted to compensate for the error between the clock readings, if any. When the sensors show abnormal readings, or readings indicating a condition of interest, the time in which they are recorded in the memory device 205 is recorded as observed. The acoustic emissions received close to 1 i I The time of the observation is then compared with the record of when those emissions were sent from the transmitting station. The emissions sent and the emissions received are counted by counting the number of emissions sent by the transmitting station | and the number of emissions received by the receiving station since the start of the cleanup of the block through the pipeline. The time delay between sending and receiving each broadcast, multiplied by the speed of sound of that frequency in the liquid that is in the pipe, provides the measurement of the distance between the detection unit and the receiving station at the time the emission was sent. This precisely locates the site of the detection unit, and therefore the sensor, when the anomalous signals were sent by the sensor, so that additional tests or repair of the pipeline can be carried out. i EXAMPLES! Example 1 - Water Pipe: In a 91.44 cm (36 inch) diameter pipe filled with potable water at a pressure of approximately 1.38 MPa (200 psi), emissions were transmitted from a transmitting station over 1 i 52-693 water detection unit in the pipeline and were successfully received at a receiving station in an inspection port of the pipeline at a distance of 800 m. The detection unit was a ball-type sensor unit of the type shown in the application; PCT Published O 2006/081671, rolling along the bottom i of the pipe. The emissions were 25 ms. of duration at a frequency of 40000 Hz.

Example 2'- Oil Pipe In a 25.4 cm (10 inch) diameter pipe, filled with crude oil at a pressure of approximately 1.38 MPa (200 psi), they were transmitted j emissions from a transmitting station on; a detection unit through the oil in the pipeline and were successfully received at a receiving station at a cleaning taps launching station at a distance of 200 m. The detection unit was a ball-type sensor unit of the type shown in the published PCT application WO 2006/081671, rolling along the bottom of the pipe. The emissions were 25 ms in duration at a frequency of 30000 Hz.

I Example 3 - Natural Gas Pipe i In a 200-ram natural gas pipeline diameter, with gas at a pressure varying between approximately 103 kPa and 270 kPa, emissions were transmitted from a transmitting station on a detection unit through the gas in pipe j and were successfully received at a receiving station in an inspection port at a distance of 50 m. The detection unit was a ball-type sensor unit of the I type shown in the published PCT application. Or 2006/081671, rolling along the bottom of, the pipe. The emissions were 25 ms in duration j a frequency of 65000 Hz.

It is understood that the invention has been described with respect to specific modalities, and that other modalities will be apparent to someone with experience in the art. Therefore, the full scope of the invention is not limited by the particular modalities, but will be considered! That the appended claims provide the invention with I total protection to which it is directed. 1 52-693

Claims

1. An apparatus for locating an object in a pipe, comprising: a transmitting station having a means for transmitting acoustic emissions in the pipeline; that have a frequency in the range of 20 KHz to 200 I KHz, a receiving station having a receiver capable of receiving the acoustic emissions transmitted by the transmitting station, | one of the receiving station and the transmitting station is located in a known position on the pipe and the other of the receiving station and the transmitting station is located on said object and a clock means to determine the time it takes for the acoustic emissions in moving between the transmitting station and the receiving station.

2. An apparatus for locating an object in motion within a pipeline, comprising: a transmitting station on said object i that it has a means to transmit acoustic emissions in the pipeline that have a frequency in the range of 20 KHz to 200 KHz, a first clock means associated with the transmitting station to transmit the emissions 52-693 acoustic at known times or at predetermined intervals, a receiving station on the pipe at a known location and having an acoustic receiver capable of receiving the acoustic emissions transmitted by the transmitting station, and a second clock means associated with the receiving station to determine the times at that acoustic emissions are received by the receiving station. i

3. An apparatus according to claim 2, wherein an error is known, if any, between the reading of the clock means associated with the transmitting station and the reading of the clock means associated with the receiving station.

4. An apparatus according to any of claims 1-3, wherein it includes recording means associated with the transmitting station 'for recording acoustic emissions sent by the transmitting station and recording means associated with the receiving station for recording acoustic emissions received by the station. receiver |

5. An apparatus according to any of the preceding claims, wherein the object is a I detection unit equipped with at least one sensor 52-693 i to detect at least one abnormal condition in the pipeline. i

6. An apparatus according to claim 5 ', wherein the sensor is equipped in such a way that the detection of an abnormal condition by means of the sensor causes the transmitting station to transmit! an acoustic emission. i

7. An apparatus according to any one of the preceding claims, wherein the means for transmitting acoustic emissions transmits emissions (having a frequency in the range of 20 KHz to 100 KHz. i

8. A method for determining the position of an object in a pipe which contains fluid, comprising: transmitting in the pipe acoustic emissions that have a frequency in the range of 20 KHz to 200 KHz from the object inside the pipe, receive the acoustic emissions in a known position on or inside the pipeline, determine the time it took: I acoustic emissions in moving between the object and the known position, and determine the speed of sound in, the fluid i in the pipe. i 52-693 1 I

9. A method for determining the position of an object in a pipe which contains fluid, comprising: transmitting in the pipe acoustic emissions having a frequency in the range of 20 KHz to 200 KHz from a known position on or within the pipeline, receive the acoustic emissions in the object, determine the time it took for the acoustic emissions to move between the known position and the object, and determine the speed of sound in the fluid in the pipeline. [ I

10. A method according to any of claims 8 or 9, wherein the acoustic emissions have a frequency in the range from 20 KHz to 100 KHz. '

11. A method according to any of claims 8-10, wherein the acoustic emissions have a duration in the range of 1 millisecond to 200 milliseconds. 52-693 I